For a long time there has been a need for a liquid fabric-softening, fine detergent which imparts to fabrics desired softening and antistatic properties during the washing process. Because of the known incompatibility of the conventional quaternary ammonium or imidazolinium fabric softeners with anionic surfactants, it has been impossible to use anionic surfactants in such liquid preparations. Therefore combinations of nonionic surfactants and quaternary ammonium compounds have been employed. Liquid detergents having such combinations are known from British Pat. No. 830,864, which discloses compositions containing nonionic surfactants and quaternary ammonium compounds with a long-chained alkyl radical and three short-chained alkyl radicals. According to the Journal Seifen-Ole-Fette-Wachse (1963) 4, p. 78, the washing effect of these combinations is particularly good if the ratio of the nonionic surfactant to the quaternary ammonium compound is in a quantitative ratio of 4:1 to 1:1.
Other nonionic surfactant-quaternary ammonium compound compositions are known. For example, DOS No. 2,426,581 describes a combination of a nonionic surfactant, a conventional softening quaternary ammonium compound with one or two long-chained alkyl radicals, as well as another quaternary ammonium compound with a methyl group, one or two long-chained alkyl groups, and one or two polyglycol ether groups. A liquid detergent comprised of a nonionic surfactant of the type of the alkyl polyglycol ethers or alkylphenol polyglycol ethers and a conventional fabric softener of the type of the di-higher-alkyl-dimethyl ammonium halides, as well as of a fatty acid polyglycol diester, is also known from DOS No. 2,529,444.
These liquid detergent compositions have not, however, been satisfactory, because no balance can be achieved with these detergents between washing ability, fabric-softening cpacity and sudsing behavior. U.S. Patent Application Ser. No. 032,467, filed Apr. 23, 1979, suggests that the disadvantages inherent in these detergents can be avoided by using a liquid detergent with a wash-active component of two defined nonionic surfactants of the type of the ethoxylated long-chained alcohols and with a softening component of a quaternary ammonium compound. The quaternary ammonium compounds used are particularly ammonium salts with two long-chained alkyl or alkenyl groups and two short-chained alkyl groups, particularly those compounds whose long-chained radicals are derived from saturated or unsaturated tallow fat alcohols, such as alkyl and alkenyl groups having 16 or 18 carbon atoms, examples of which include palmitoleyl, stearyl, oleyl, and linoleyl radicals.
The consumer demands that in addition to having satisfactory washing properties, a modern liquid detergent must be safe in use and stable in storage, and that it must meet certain expectations in terms of appearance and odor. In particular, the perfuming of a detergent must meet high standards. Not only does the favorable acceptance of a detergent frequently depend on whether it has a pleasant odor, but also the detergent perfume must effectively mask the frequently unpleasant odor of the wash liquor, thus supplementing the desired washing results by imparting to both freshly laundered damp wash and dry wash an odor giving the impression of cleanliness and freshness.
During the production of liquid detergents based on nonionic surfactants, which comprise from about 10 to 30% by weight, it has frequently been difficult to incorporate the necessary quantities of nonionic surfactants with conventional fabric softeners of the type of distearyldimethyl ammonium chloride or ditallow alkyldimethyl ammonium chloride with hardened tallow alkyl radicals, because of the low water solubility of these compounds. This has lead to mixtures that have been thickly liquid and difficult to pour, particularly at low storage temperatures, and therefore have required the use of large quantities of organic solvents. Though the perfuming of these mixtures has presented no problem, it has seemed advisable due to the unfavorable viscosity properties, to switch to other fabric softeners which do not have these drawbacks.
Other quaternary ammonium fabric softeners are known, such as derivatives of the unhardened tallow alcohols which contain particularly oleyl, but also palmitoleyl and linoleyl, radicals in a total amount of about 45% by weight. Although the mixtures prepared with this type of compound have desired viscosity properties, which are to a great extent independent of the temperature, such perfumed mixtures are not stable in storage. The lack of stability is manifested by a change of the odor to an unpleasant smell, as well as by a change in color of the liquid. The same observations have also been made with corresponding imidazolinium compounds having saturated or at least partly unsaturated long-chained aliphatic groups.